1. Field of the Invention
The present invention relates to a method of manufacturing a vacuum device utilizing a sputtering process, and more particularly, to a method of manufacturing a vacuum device which is operated by applying an electric field to an electrode such that electrons is emitted from the electrode (hereinafter, referred to an emitting electrode or cathode electrode) in the presence of a vacuum or a specific gas.
2. Description of the Related Art
In general, the efficiency of a vacuum device using an electron emission depends on the shape of emitting electrodes. That is, in order to converge the electric field into the end of the emitting electrodes, the emitting electrodes are important parameters to obtain a high electric field on how the end of the emitting electrodes is sharpen and on how the emitting electrodes are closely positioned to a gate electrode which excites the emitting electrodes. Therefore, the more the end of the emitting electrodes is sharpen and the emitting electrodes are closed to the gate electrode, the more the improved efficiency of the vacuum device can be manufactured. This is a measure which is capable of lowering the drive voltage of the device. Further, it has an advantages that the drive circuit is simplified and the drive circuit by the high voltage is not necessary.
Now, the problem of the vacuum device in the prior art will now be described with reference to FIGS. 1A and 1B more in detail.
FIG. 1A illustrates a silicon-type electric field emission device of the conventional vacuum device. In Fig. 1A, it represents that an emission electrode 2 is formed on a silicon substrate 1 by an isotropic etching method. An insulating layer 3 is formed on a portion of the silicon substrate 1 and a gate electrode 4 is then formed on the insulating layer 3 using Molybdenum(Mo), Tungsten(W) or a metal having a high melting point, as shown in FIG. 1A, such that in use an electric field is applied to the emission electrode 2.
According to the structure, there is a problem that the distance between the emission electrode and the gate electrode must exceed the size of the minimum tolerance of the mask pattern used when the silicon substrate is etched by using the isotropic etching method.
Referring now to FIG. 1B, it illustrates a metal-type electric field emission device of the conventional vacuum device. In the drawing, an emission electrode 2 is formed on an insulating substrate 5 made of a silicon or a glass by a vacuum evaporating deposition method. An insulating layer 3 is formed on a portion of the insulating substrate 5 and a gate electrode 4 is then formed on the insulating layer 3 using Mo, W or metal having a high melting point, as shown in the drawing. According to the structure, the insulating layer 3 is formed and a predetermined mask pattern is defined thereon first. The sharp ended emission electrode 2 is then formed in the pattern so defined by forming the gate electrode 4 by an electron-beam deposition method using Mo, W or the metal having a high melting point.
In this embodiment of the conventional structure, a problem still exists that the distance between the emission electrode and the gate electrode must exceed the size of the minimum tolerance of the mask pattern as previously described above.
But In view of the aspect of improving the operational characteristics of the device, since the distance between the emission electrode and the gate electrode is influenced directly to the electric field which determine the emission current, a need exists that the distance between the emission electrode and the gate electrode should be minimized. Therefore, a problem is encountered that to minimize the distance between the emission electrode and the gate electrode will make the manufacturing process for forming the fine mask pattern more complicated. This further requires an expensive apparatus for forming the fine mask pattern and even with the use of the apparatus, it is so difficult to obtain an uniform distance therebetween.
It is therefore an object of the invention to provide a method of manufacturing a vacuum device utilizing a sputtering process in which a gate electrode so formed can be easily closed to the emission electrode using the sputtering method and the vacuum device can be operated with the desired low voltage by controlling the distance between the emission electrode and the gate electrode.